In general, a mobile communication system has a function part for calculating the position (or location) of a terminal in a mobile communication network to provide a location service that provides the location of the terminal to a certain entity in a periodic manner or according to a corresponding request.
A network structure related to the location service differs depending on an internal network structure, such as a 3GPP network, a 3GPP2 network, etc. Currently, there are several methods for calculating the location of the terminal, including a cell-ID method for transferring an ID of a cell to which a mobile terminal belongs, a method for calculating the location of a terminal through triangulation by measuring time taken for radio signals to reach each base station from the terminal, and a method of using a GPS (Global Positioning System).
In order to provide the location service to a user, a large quantity (amount) of signals and location information are to be transferred between the mobile terminal and a location server.
Recently, positioning technologies standardized for providing the location service (namely, location services provided based on the location of a mobile terminal) are increasingly used. These technologies can be provided generally through a user plane for transmitting user data and a control plane for transmitting control data, one of which is a Secure User Plane Location (SUPL) technique that provides the location service through the user plane.
A SUPL-based network includes a SUPL agent, a SUPL location platform (SLP), a SUPL enabled terminal (SET), and the like. The SUPL agent is a logical service access point that requests location information of a target SET from the SLP, receives measured location information of the target SET from the SLP, and uses it. The SLP is an entity that accesses network resources to obtain location information of the target SET according to a request from the SUPL agent, and performs roaming and resources management, and the like. The SET performs procedures defined at the SUPL along with the SLP through a user plane bearer.
There are two types of location services based on the SUPL: The first service refers to a periodic triggered service that provides the location of the target SET (i.e., terminal) according to a pre-set period; the second refers to an area event triggered service that provides the location of the target set (i.e., terminal) when pre-set conditions in relation to a particular area are met.
The area event triggered service will now be described in detail with reference to FIGS. 1 to 3.
FIG. 1 illustrates the concept of an area event triggered service according to the related art.
As shown in FIG. 1, there are four types of area event triggered services. In FIG. 1, the points at which location measurement is made are indicated as asterisks.
As shown in FIG. 1(a), a first area event triggered service is a location service for continuously monitoring whether the terminal 10 is located in a previously designated geographic area 50, which is also called an inside location service. A second area event triggered service as shown in FIG. 1(b) refers to a location service that monitors whether or not the terminal 10 enters the previously designated geographic area 50, which is also called an entering location service. A third area event triggered service as shown in FIG. 1(c) refers to a location service that continuously monitors whether the terminal 10 is located outside the previously designated geographic area 50, which is also called an outside location service. A fourth area event triggered service as shown in FIG. 1(d) refers to a location service that monitors whether or not the terminal 10 leaves the previously designated particular geographic area 50, which is also called a leaving location service.
FIG. 2 illustrates implementation of the area event triggered service as shown in FIG. 1.
As shown in FIG. 2(a), in order to implement the location service (inside service) as to where the terminal is located within the previously designated geographic area 50 or the location server (entering service) as to whether or not the terminal 10 enters the previously designated geographic area 50, an area-id parameter has been proposed. The area-id parameter is a list of IDs of cells. In case of the inside service and the entering service as shown in FIG. 2(a), the Area-id parameter includes a set of IDs of cells fully included in the previously designated geographic area 50. In case of the inside service, when the area-id parameter is provided, the terminal 10 compares a cell-id of a cell in which the terminal 10 is currently located with a cell-id in the Area-id parameter, and if the both cell-ids are consistent, the terminal 10 performs a position estimate (A-GPS) to monitor whether the terminal 10 is located in the previously designated geographic area 50. In addition, in case of the entering service, when the Area-id parameter is provided, the terminal 10 compares a cell-id of a cell in which the terminal 10 is currently located with a cell-id of the Area-id parameter, and if the both cell-ids are consistent, the terminal performs a position estimate to monitor whether the terminal 10 has entered the previously designated area 50.
As shown in FIG. 2(b), when the terminal 10 is outside the previously designated geographic area 50, the Area-id parameter may be used to implement the outside location service that keeps monitoring the location of the terminal 10 and the leaving location service that monitors whether or not the terminal 10 leaves the previously designated geographic area 50. In this case, the Area-id parameter includes a set of the IDs of the cells fully included in the previously designated geographic area 50. In case of the outside service, when the Area-id parameter is provided, the terminal 10 compares a cell-id of a cell in which the terminal 10 is currently located with a cell-id in the Area-id parameter, and if the both cell-ids are not consistent, the terminal 10 performs a position estimate (A-GPS) to monitor where the terminal 10 is located outside the previously designated geographic area 50. In case of the leaving service, the terminal 10 compares a cell-id of a cell in which the terminal 10 is currently located with a cell-id in the Area-id parameter, and if the both cell-ids are not consistent, the terminal 10 performs a position estimate to monitor whether or not the terminal 10 leaves the previously designated geographic area 50.
FIG. 3 illustrates the leaving location service among the area event triggered service as shown in FIG. 1.
As shown in FIG. 3, when the Area-id parameter is provided in the leaving location service likewise as above-described, a position estimate may be continuously performed unnecessarily as follows.
Such problem may arise when a repeated reporting function is used in the area event triggered location service. Namely, when a service requestor requests using of the repeated reporting function while requesting the leaving location service, a position estimate needs to be performed only on whether or not the terminal 10 has leaved the previously designated geographic area 50, but previous positioning is continuously performed as shown in FIG. 3.
In detail, it is assumed that the Area-id parameter is provided as shown in FIG. 3 and the terminal 10 moves along the path indicated by a dotted line.
While moving along the path indicated by the dotted line, the terminal 10 compares a cell-id in the provided Area-id parameter and a cell-id of a cell in which the terminal 10 is located. If the both cell-ids are not consistent, the terminal 10 performs a position estimate and reports the positioning result. The position estimate continues until when the terminal 10 completely leaves the previously designated geographic area 50. When the terminal 10 is determined to have been completely out of the previously designated geographic area 50, the terminal 10 reports the result.
Thus, although the terminal 10 gets completely out of the previously designated geographic area 50, the repeated reporting function is still used, so the terminal 10 keeps a position estimate and reporting the result.
Thereafter, even if the terminal 10 enters the previously designated geographic area 50, there is a possibility that the terminal 10 leaves the previously designated geographic area 50 until before it completely enters a cell having an id consistent to the cell-id of the provided Area-id parameter, so the terminal 10 keeps a position estimate.
However, because the terminal 10 does not enter the cell having the id consistent to the cell-id in the Area-id parameter along the path indicated by the dotted line, the terminal 10 keeps a position estimate.
As mentioned above, in case of using the repeated reporting function, although the terminal 10 has left the previously designated geographic area 50, the terminal keeps a position estimate until before it enters the cell having the id consistent to the cell-id in the provided Area-id parameter.
Thus, continuously performing the a position estimate wastes not only resource of the terminal 10 but also the network resources.